T98 Earth Life Transitions and Major Continental Biological Events of the Phanerozoic

Monday, 23 October 2017
8:00 AM - 12:00 PM
Room 611

LATE PALEOZOIC GLOBAL SEAWATER 87SR/86SR AND δ13C RECORDED IN SOUTH CHINA PROVIDE INSIGHTS INTO EARTH’S PENULTIMATE ICEHOUSE

Paper number: T98-4
Program: Technical Sessions
Time: 8:35 AM – 8:50 AM

Authors

  • Jitao Chen Presenting Author
    University of California, Davis, Davis, CA
  • Jitao Chen Presenting Author
    Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing
  • Isabel Montanez
    Univ California - Davis Dept. of Earth and Planetary Sciences, Davis, CA
  • Yuping Qi
    Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing
  • Xiangdong Wang
    Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing

Abstract

Earth’s penultimate icehouse (~340–285 Ma) was a time of low atmospheric pCO2, dynamic glaciation on Gondwana, formation of supercontinent Pangea, and radiation of the oldest paleo-tropical rainforests. Although it has been long appreciated that these major tectonic, climatic, and biotic events would have left their signature on seawater 87Sr/86Sr through their influence on Sr fluxes to the ocean, the temporal resolution and precision of the Carboniferous–Permian seawater Sr isotope record remains relatively low. Here we present a high temporal resolution and high-fidelity record of Carboniferous seawater 87Sr/86Sr based on conodont apatite from an open-water carbonate slope succession in south China. The new data refine the structure of the long-term rise in seawater 87Sr/86Sr from the Middle Mississippian through Early Pennsylvanian (~338–318 Ma) and document a rate of rise (from 0.7077 to 0.7082) comparable to that of Neogene seawater Sr. The onset of the previously documented decline in seawater 87Sr/86Sr is constrained to 301 Ma and follows a plateau through the Late Pennsylvanian (318–301 Ma). Coupling the 87Sr/86Sr and carbonate δ13C records provides insight into relative roles of continental weathering, expansion and retraction of the tropical wetland rainforests, widespread aridification and global-scale emplacement of basaltic provinces on atmosphere pCO2 during Earth’s penultimate icehouse.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-301283

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